Typical heat exchangers comprise manifolds having apertures in which cooling core tubes are inserted. In such heat exchangers, the cooling core tubes remain in contact only with one wall of a tank. The surface of the resultant joint is therefore small, which decreases the rigidity of construction.
A solution to this problem is presented in U.S. Pat. No. 5,842,515, which discloses a heat exchanger comprising manifolds having flat bottomed portions formed with a plurality of apertures for receiving a plurality of corresponding heat exchanging tubes, a pair of vertical walls extending from opposing sides of the flat bottom portion and having a plurality of grooves corresponding to the apertures for guiding the tubes. A pair of connecting portions extending transversely or bulging outward from the vertical walls is provided and joined together in order to form a hollow inner space and to define the outer surface of the manifold.
Another solution to the problem is proposed in U.S. Pat. No. 5,743,329, the specification of which discloses a heat exchanger having a manifold with an outer and an inner casing, and comprising at least one slot lying in a plane roughly perpendicular to a longitudinal axis of said manifold, said slot being defined by narrow sides which are limited by parallel-running slot walls of the manifold which extend roughly along a tangent to a circle around the manifold longitudinal axis. The slot width is equal to at least the manifold inner diameter and therefore the slots are capable of accepting flat heat exchanging tubes. The walls of the slots are formed from deformed wall portions of the manifold having a constant wall thickness, and the outer sides of the slot walls lie outside the outer casing of the manifold. The inner sides of said slot walls are offset radially outward relative to the manifold inner casing and a shoulder is formed between the slot walls and the manifold inner casing.
An object of the present invention is to provide a heat exchanger having an improved rigidity of construction, where the manifolds are connected with the ends of heat exchanging tubes in a stable and precise manner. Another object of the present invention is to provide an uncomplicated and robust method of manufacturing heat exchanger manifolds, which facilitates preliminary assembly and manufacture of the heat exchanger manifolds such that they may subsequently be incorporated into the resultant heat exchanger.